The present invention relates to actuators for emergency operation, and more particularly to an actuator in which a small-sized container such as a gas bottle or cylinder charged with compressed high pressure gas is detachably attached to an actuator mechanism in communication with an operation chamber thereof. The high pressure gas in the container is expelled or discharged in an emergency, and causes the actuator mechanism to be driven by the discharged high pressure gas as a working fluid.
In general, actuators driven by compressed gas as a working source have been designed heretofore so as to be driven by compressed air from a driving power source such as an air compressor installed outside thereof. This practice is accompanied by difficulties such as complicated structural organization and requirement for large installation space.
In an equipment for supplying city gas and for pipelines in petroleum chemical plants, emergency shut-off valves adapted to close when emergency situations such as earthquakes and fires occur are installed at important points of the supply pipeline. As means for driving an emergency shutoff valve of this type, an actuator has heretofore been used. In this case, however, there arise problems such as bulky equipment and the requirement that the air compressor is driven continuously even in a normal state in preparation for an emergency situation, whereby the power cost and maintenance cost amount to a large sum. Further, in the probable case where the air compressor is damaged simultaneously with the occurrence of an earthquake, the actuator is not driven at all, and the emergency shut-off valve does not operate to serve its intended purpose. As a result, there arises the serious problem of a secondary accident induced by the earthquake not being prevented from occurring.
Furthermore, installation of the emergency shut-off valve having the aforementioned actuator in existing equipment for supplying city gas entails a difficulty in that the additional equipment required is considerably complicated and expensive.